摘要:

After restoration by whole-lake applications of liquid aluminum sulfate, Medical Lake, Washington, received a total planting of approximately 31,000 fingerling rainbow trout (Salmo gairdneri) from 1978 to 1980. Prior to treatment the lake had been unable to support game fish. Post-treatment improvement in water quality and zooplankton standing crops permitted good trout survival and growth.Daphnia pulexcomprised over 90 percent of the trout diet for most age classes and dominated the biomass of the 0+ age class.

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664571

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Hatchling desmognathine larvae and pre-metamorphic larvae ofDesmognathus fuscuswere found in 16 of 78 low order streams from coal surface mine impacted areas of the Cumberland Plateau. Although larvae were found to be surviving in a wide range of pH values, they were limited in range by high concentrations of dissolved solids (probably metal salts) in combination with acid conditions. The loss of shading (tree removal) resulted in increased turbidity and siltation which probably eliminated preferred habitat. I suggest that many species of the desmognathine complex, some of which are considered rare and protected, can be used as effective indicators of surface mine impacts, particularly heavy metal contamination and other effects associated with low pH conditions.

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664572

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Paired samples taken from 100 lakes during July, 1980, were examined for desmids and anlayzed chemically. Simple linear regression analyses comparing desmids with pH, conductivity, alkalinity, calcium, magnesium, sodium, and potassium indicated very little statistical correlation between numbers of species and any single chemical factor. Stepwise regression for pairs of chemical values produced highest R-square for pH and magnesium (0. 21139) but not positively significant.

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664573

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Subsequent to the 1977 lake restoration through whole-lake applications of alum (aluminum sulphate), Medical Lake, Washington, has supported an experimentally stocked rainbow trout (Salmo gairdneriRichardson) population. Because these fish and their prey are dependent upon habitat potentially higher in available aluminum than neighboring habitats, this study was undertaken to assess the possibility of aluminum bioaccumulation. Trout tissues, plankton and water were analyzed for total aluminum concentrations. Statistical comparisons of experimental and control tissues revealed few overall significant differences (P = 0.05) in the level of aluminum between alum-exposed and non-exposed fish, but significant differences existed between tissues within a given treatment and age class.

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664574

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Functional responses of wild brown trout (Salmo trutta) to drifting brine shrimp (Artemia salina) were studied in a laboratory stream. The general form of the response was Type II, although considerable individual variation was detected in parameters related to attack rate and handling time. The disc equation (Holling 1959) accounted for up to 76% of the variation in prey consumption. Threshold rates of prey capture or drift density seemed to characterize some individuals, but general value could not be specified. Maximum predation rates of 10.8 prey min−1were sustained during feeding bouts of 30 min; short-term peaks of 18 prey min−1were recorded. Analyses of functional responses show promise in future studies of stream communities, particularly with regard to epibenthic foraging.

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664575

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

We describe an experimental enclosure for use in lentic habitats which is relatively inexpensive, easily constructed, and conveniently stored between experiments. The basic design is quite versatile. Enclosures can be built in sizes ranging from 4 inches (10 an) to 17 inches (43 cm) in diameter (area of bottom—81 to 1464 square centimeters); the mesh size of the sides may be varied; and the tops may be open or closed by a clear plastic lid. Results of independent one-month-duration experiments suggest no “enclosure effects” on water temperature or dissolved oxygen concentrations. Comparison of benthos densities within enclosures and in open sites located nearby in the saw habitats indicate that most taxa exhibited similar changes in abundance under the two conditions; some exceptions are attributable to exclusion of certain predators from the enclosures; and a few cases suggest that certain insect taxa may have experienced reduced recruitment when enclosure tops were closed.

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664576

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A limnological survey of 9 lakes located in the sandhills of northwestern Florida was conducted to determine general physical, chemical, and biological characteristics. Lake mean depth ranged from 6.3 to 27 m. Secchi disc values ranged from 3.2 to 8.1 m. Thermal stratification occurred in all lakes. Chemically, the lakes can be characterized as acidic, soft-water lakes of low mineral content. Average total phosphorus values ranged from 3.1 to 10 mg/m3, and average chlorophyllavalues ranged from 0.5 to 1.4 mg/m3. These lakes are among the most oligotrophic lakes in Florida.

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664577

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The forage fish assemblage of the Brazos River was sampled at one location above and four locations below Possum Kingdom Reservoir each month for one year. A total of 13,936 individuals representing 18 species, 14 genera and five families were collected. Five of these species,Notropis stramineus, Notropis atherinoides, Hybognathus placitus, Hybopsis aestivalis and Cyprinodon rubrofluviatiliswere found only upstream from Possum Kingdom Reservoir.Hybognatus placitusaccounted for 45% of fish captured at the upstream site. In contrast, nine species were collected exclusively in the tailwaters, includingEtheostoma spectabile, Percina sciera, Campostoma anomalum, Notropis venustus, Pimephales notatus, Labidesthes sicculusandFundulus notatus. Only four species were obtained at all five stations—Gambusia affinis, Menidia beryllina, Pimephales vigilax and Notropis lutrensis. N. lutrensiswas the most common tailwater species equalling 87.9% of the total downstream catch. Median species diversity indices ranged from 0.129 to 0.451 for the five stations, with the highest value at the upstream station. Coefficients of biotic similarity ranged from 0.20 to 0.62, with the upstream station clearly being the most dissimilar. These findings are discussed relative to environmental effects of hypolimnetic release of reservoir waters.

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664578

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The sequence of qualitative and quantitative changes in the chironomid fauna of Laurel Creek Reservoir over the thirteen years of its existence are presented. There was a substantial decrease in the average numerical abundance Pram 1967 (6303m−2) to 1968 (3373m−2), and it has remained stable since (3166m−2in 1975, 2856m−2in 1980). There have been distinct changes in the faunal numerical abundance, although the genera have remained the same. In 1967, the Chironomini (Chironomus>Glyptotendipes) comprised 95% of the total throughout the year. In 1968, the Chironomini dominated (68%) the Tanytarsini increased (24%) and the Tanypodinae (6%) and Orthocladiinae (2%) remained low. In 1975, the Chironomini (Chironomus>Glyototendipep≈Cladopelma) (72%) and the Tanypodinae (Procladius) (21%) increased, the Tanytarsini decreased (5%) and the Orthocladiinae remained low (2%). By 1980, the Tanypodinae (Procladius) had become dominant (60%) while the Chironomini (Chironomus>Cladopelma>Glyptotendipes) had decreased (38%). The Tanytarsini and Orthocladiinae were insignificant (1% each). The decreased standing stock and changes in the dominance hierarchy of the chironomid fauna are associated with changes in the trophic level of the substrate conditions and bottom oxygen levels of the reservoir.

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664579

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1983.9664580

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor